What must be done to openings in a tank shell that exceed the size necessary for accommodating an NPS 2 nozzle?

• A. They should remain unchanged
• B. They shall be reinforced
• C. They may be covered with a cap
• D. No special measures are needed

Answer: (B)

When openings in a tank shell exceed the size necessary for accommodating an NPS 2 nozzle, it is essential to reinforce these openings. This requirement stems from the need to maintain the structural integrity and safety of the tank under various operating conditions. Larger openings can impose additional stresses and reduce the overall strength of the tank shell. Reinforcement helps to ensure that the tank can safely accommodate the increased loads and does not compromise its ability to contain the liquid it is storing.

Reinforcement can be achieved through various methods, such as adding reinforcing plates or using specifically designed rings around the opening. These measures are integral to adhering to the standards set forth in API 650, which prioritize safety and reliability in tank design and construction. Therefore, the requirement for reinforcement is an essential aspect of maintaining the overall durability of welded tanks for oil storage.